The present invention relates to an antenna apparatus. More specifically, the present invention is directed to a connection structure for causing a rod antenna mounted on a top cover to be connected with respect to a circuit board.
As is well known in this technical field, various sorts of antenna apparatuses are presently mounted on vehicles. For instance, antennas designed for receiving AM/FM radio waves are provided. Generally speaking, a rod antenna is used for such antennas.
An antenna apparatus equipped with the rod antenna is constructed with following structure. The rod antenna is mounted on a top cover. The top cover is combined with a base so as to form an antenna case. The antenna cover accommodates a circuit board mounting an amplifying circuit (booster circuit). The rod antenna is supported and fixed on the top cover by a supporting metal fitting (connector). The supporting metal fitting receives a reception signal received by the rod antenna.
In the antenna apparatus having above-described structure, the rod antenna is required to be electrically connected to the circuit board (namely, amplifying circuit). Various sorts of such connection structures are proposed.
Patent Document 1 discloses an antenna apparatus wherein a conductive member is mounted on an upper face of a circuit board. An amplifying circuit is arranged on a lower face of the circuit board. The conductive member is connected to a rod antenna so as to be electrically connected to the amplifying circuit. As will be later explained with reference to FIG. 1, in this case, a first end portion of a rod-side terminal (contact), a second end portion of which is mounted on a connector, and the second end portion of the rod-side terminal must be inserted into the conductive member in order to establish electric connection.
Patent Document 2 discloses a contact which connects an amplifying circuit with a rod antenna. This contact is formed from an elongated metal sheet so as to continuously include a flat portion, a contact portion and a mounting portion. The contact portion is adapted to come in contact with the rod antenna, and extends obliquely relative to the flat portion. The mounting portion is projected from the flat portion to an opposite side of the contact portion, and formed with claws. When the mounting portion is inserted into a hole formed on the circuit board, the claws engage with the edge of the hole to firmly retain the contact on the circuit board.
[Patent Document 1] Japanese Patent Publication No. 2007-013273 A
[Patent Document 2] Japanese Patent Publication No. 2002-151927 A
With reference to FIG. 1, there will be described a conventional antenna apparatus 10 having such a connection structure that is disclosed in Patent Document 1.
The antenna apparatus 10 has an antenna case and a rod antenna 20. The antenna case is constituted by a top cover 25 and a die casting base 60. The rod antenna 20 is mounted on the top cover 25. The rod antenna 20 is configured to receive radio waves of AM, FM, telephonic bands. A circuit board 15 mounting an amplifying circuit (not shown) is stored in the antenna case. The rod antenna 20 is arranged in such a manner that the rod antenna 20 is inclined from a vertical line. The rod antenna 20 is fixed and supported on the top cover 25 by a connector 30. Signals received by the rod antenna 20 are input to the connector 30.
A conductive member 80 is mounted on an upper face 15a of the circuit board 15. The conductive member 80 is connected to the rod antenna 20 in the following manner so as to be electrically connected to an amplifying circuit.
The antenna apparatus 10 comprises a rod-side terminal (contact) 40. A first end portion 40a of the rod-side terminal (contact) 40 is mounted on the connector 30, whereas a second end portion 40b of the rod-side terminal (contact) 40 is inserted into the conductive member 80 so as to be electrically connected to the conductive member 80.
A lower face of the die casting base 60 is covered by a base pad 70. The lower portion of the die casting base 60 is formed with a boss 65, in order to mount the antenna apparatus 10 on a roof panel of an automobile (not shown). Also, one terminal portion of an output cable (not shown) is connected to the circuit board 15, and the die casting base 60 is formed with a hole (not shown) in order to lead the output cable to exterior of the top cover 25.
Since the connection structure of such a conventional antenna apparatus 10 comprises the rod-side terminal (contact) 40 and the conductive member 80, a total number of the components is increased. As a result, the manufacturing cost is increased. Also, since the above-described connection structure of the antenna apparatus 10 is made of two components, an assembling work of the connection structure cannot be facilitated. Furthermore, the conductive member 80 is mounted on the upper face 15a of the circuit board 15. As a result, a space for mounting the conductive member 80 must be provided, so that the height of the antenna case can be hardly reduced.
On the other hand, the contact disclosed in the Patent Document 2 has such a complex structure. Also, since the circuit board must be formed with the through hole, the area of the circuit board is enlarged. As a result, the antenna apparatus becomes bulky.